Low temperature sulfonation process



United States Patent LUW TEMPERATURE SULFONATION PROCESS Charles F. W. Gebelein, Butler, Pa., assignor to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application September 1955 Serial No. 533,503

3 Claims. (Cl. 260-504) This invention relates to an improved low temperature process for the preparation of oil and water soluble sulfonates. More particularly it relates to an integrated process for the preparation and recovery of these differing sulfonates.

The sulfonation of petroleum oils to oil and Water soluble sulfonates is well known. Recent work has shown that considerable quantities of the oil soluble derivatives are present in the acid sludge layer. This decreases the yields of the desired products. In addition it is known that oil soluble sulfonates are lost by degradation reactions including those which convert potential feed for oil soluble products to Water soluble products. In some cases this loss has been found to be equivalent to between 50 and 100% of the oil soluble sulfonic acids recovered in the acid oil in the conventional manner. Furthermore co-solvency effects of the oil and water soluble sulfonates have prevented sharp separations in the stratifying procedures utilized. All of these factors have contributed to diminished yields.

The present invention provides an improved process for preparing and recovering high yields of oil and water soluble sulfonates free of the beforementioned difliculties. In brief summary, the process comprises treating a petroleum oil feed dissolved in liquid sulfur dioxide at low temperatures with a single treat of a sulfonating agent. The mixture is neutralized in the presence of a low alcohol. The crude alcoholic soap solution is then countercurrently extracted according to this invention with an organic solvent and the different type sulfonates recovered.

The invention will now be further explained in greater detail.

The petroleum hydrocarbon oil feed stocks can be utilized include feed stocks which may or may not have been previously acid treated, deasphalted, dewaxed or extracted with solvents such as ketones, nitrobenzene, phenol, cresol, chlorex, etc., or which may be a distillate, neutral or bright stock or mixture of these, but is still reactive with sulfuric acid. These feed stocks can be obtained from crudes which are either predominantly parafiinic or naphthenic in character, both of which contain appreciable proportions of aromatic constituents. Synthetic feeds can also be used such as C polypropyl benzene alkylate bottoms and are intended to be included.

These oil feed stocks are known generically as lubricating oil fractions. Oils which are preferred for acid treating in the practice of this invention can vary in. viscosity from about 100 to 2000 seconds Saybolt at 100 F. and thus usually boil in the range of about, 315 to 600 C. as determined by vacuum Engler distillation corrected to atmospheric pressure.

in general the oil soluble sulfonic acids as described herein are those having the general formula RSO H, where the molecular weight of the R is greater than 230. The water soluble sulfonic acids as described herein connote di-sulfonic' acids having the general formula 2,843,625 Patented July 15, 1958 ICC R(SO H) where the molecular Weight of R is less than 600.

The feed stock is dissolved in liquid sulfur dioxide, or other suitable diluents such as nitrogen, Freons (dichlorodifluoromethane and other halogenated hydrocarbons having more than one fluorine atom per molecule), butane, chloroform, etc. The ranges of hydrocarbon oil to sulfur dioxide utilized is in the range of 20 to 100 volume percent, preferably to 100 volume percent. The pressure and temperature are maintained so as to keep the S0 in the liquid state.

The solution of petroleum oil feed in liquid sulfur dioxide is contacted with a sulfonating agent in a single treat, i. e., all at one time rather than in stages. The sulfonating agents that can be employed include from 100% sulfuric acid through various stages of fuming sulfuric acid containing, for example, 25% dissolved S0, or 65% dissolved S0 up to and including a stabilized liquid anhydrous S0 available commercially as Sulfan B.

The amount of sulfonating agent employed for maximum oil soluble sulfonate production is dependent on the sulfonatable hydrocarbon concentration present in the feed stock. This may be conveniently determined in a laboratory assay employing the herein described process conditions and an excess of acid. From the yield of total sulfonate and average molecular weight of the sulfonate and hydrocarbon feed stock the mols of sulfonatable hydrocarbons in the feed stock can be closely approximated. It is preferred to employ between 3 to 7 mols of 50;, per mol of sulfonatable hydrocarbons for maximum oil soluble sulfonate production, when sulfuric acids or oleum are employed. When either gaseous or liquid S0 are employed it is preferred to use 1% mols to 3 /2 mols of per mol of sulfonatable hydrocarbon. To obtain maximum yields of total sulfonate it is preferred to use 5 to 11 mols of S0 per mol of sulfonatable hydrocarbon when oleum or sulfuric acid are employed and. 2.5 to 5 /2 mols of S0 per mol of sulfonatable hydrocarbon when liquid or gaseous 80, are employed. For maximum production of water soluble sulfonates this concentration may be increased to 30 to 45 mols of $0, per mol of sulfonatable hydrocarbon when oleum or sulfuric acid are used or 15 to 22 /2 mols of S0 per mol of sulfonatable hydrocarbon when liquid or gaseous 50, are employed. The order of addition of reagents is critical for optimum yields of oil. soluble sulfonate. The sulfonating agent, either alone or dissolved in liquid S0 should be added to the hydrocarbon feed stock solution and not the reverse order of addition.

The temperature utilized for the sulfonation is kept by refrigeration at a maximum of 0 C. and preferably a maximum of 10 C. Usually 20 to 40 minutes are required to add the oleum followed by 30 to 60 minutes additional agitation.

For purposes of carrying out the reaction a reaction vessel may be used containing a high-speed type of turbo or shear type of mixer containing means for heat exchange either through the walls of the reactor or by means of cooling coils contained within the reactor or by means of an external heat exchanger and a means of pumping the reaction mixture through the heat exchanger and returning to the reactor. Improved mixing is obtainable by introducing the reactants. directly into the suction of the impeller of a turbo mixer. The size of the reactor is determined by the rate at which the prediluted hydrocarbon feed and acid are fed to the mixing vessel and the residence time desired. For purposes of continuous operation the reactants may enter at the bottom of the reaction vessel and an overflow pipe provided at a suitable height is connected to the reactor so as to give. the desired residence time. The sulfur dioxide is then reaseaezs a moved from the resulting mixture. The S is normally removed by column stripping. Only small amounts of heat are required, it is not necessary to use vacuum, but vacuum stripping can be used to advantage in speeding the operation.

The resulting mixture is then neutralized with a basic alkali metal or alkaline earth material usually aqueous or solid caustic soda or soda ash. Several stages of neutralization can be employed. This neutralization is done in the presence of a lower, i. e. C to C alcohol. The alcohol can be added first to quench the sulfonation reaction and the neutralizing agent thereafter added or the neutralizing agent can be added first or in the alcohol solution. The temperature should be maintained at 0 C. to C. until the mass is neutralized, then the temperature can be allowed to rise to room temperature to aid in the separation of the layers, etc. The quantity of alcohols used may vary from 50 to 150 vol. percent based on the volume of feed stock but usually 80 to 100 vol. percent is used. This is on the basis of 100% alcohol. Absolute alcohol is not used in View of using aqueous neutralizing agents.

Depending upon the sulfonate to oil ratio, the sulfonates are recovered from the neutralized mass either by treating the whole mass with a hydrophobic organic solvent or by recovering a crude alcoholic soap solution and treating the solution with the solvent. When the sulfonate to oil ratio is above 1 to 4 it is preferred to recover the sulfonates directly from the whole neutralized reaction mass. It is important that the amount of sulfonate in the solution to be extracted not exceed gms./ 100 ml. and it is preferred to maintain this concentration below 5 gms./ 100 ml. The alcoholic solution of mixed sulfonates or the neutralized reaction mass is extracted by contacting with an organic solvent, e. g. benzene. It is essential that the concentra tion of sulfonate in the solvent be maintained below 1 gm./100 ml., preferably below 0.5 gm./100 ml. This minimizes the cosolubility of the water soluble sulfonates in the oil soluble sulfonate solution in the extraction solvent.

It is to be appreciated that equilibrium of the sulfonates between the alcohol and solvent phases must be avoided. It is also essential that the temperature during extraction be maintained above 125 F. The solvent and alcohol phases are separated and recovered.

It is an important feature of this invention that when the whole neutralized reaction mass is treated with hydrophobic organic solvent a finished oil soluble sulfonate product can be obtained that is suitable for commercial sale. This product is substantially free of inorganic salts and contains as diluent oil the unreacted oil from the original sulfonation feedstock.

Suitable hydrophobic organic solvents comprise benzene, xylenes, carbon tetrachlorides, Freons, etc. Especially preferred are single ringed aromatics particularly benzene.

The conversion of the alkali sulfonate salts to alkaline earth salts such as calcium or barium or magnesium is not an intrinsic part of this invention, and has been adequately described in the prior art, e. g. for purposes of reference see U. S. Patent No. 2,532,997. The alkali salts are, in general, converted in oil solution by a double decomposition reaction to the corresponding alkaline earth salts when it is desired to use the latter in lubricating oils.

The following examples further illustrate and demonstrate the advantages of this process.

EXAMPLE l.EFFECT OF ACID CONCENTRATION Table I shows the effect of oleum dump on sulfonate yield and distribution of sulfonates when Necton 60, a 500 SSU/ 100 extracted Coastal Stock is treated by the aboveprocess.

Table I.L0w temperature sulfonates of Necton 60-- Sulfonale yields and distribution This shows that regardless of the quantity of 30 wt. percent oleum used the total sulfonate produced is a mixture of oil and water soluble sulfonates of relatively low molecular weight. However, by the new process taught in this invention a maximum yield of high molecular weight oil soluble sulfonate is obtained when using 15 vol. percent of oleum, by far the more desirable product.

EXAMPLE 2.-COMPARISON HIGH AND LOW TREATING TEMPERATURE SULFONATION Table 11 presents data showing the sulfonate yield and distributions on Necton 60 treated in a single 5% dump (a) at 10 C. temperature, (b) 70 C. with neutrahzation of the entire reaction mass, (0) conventional 70 C. treatment and acid oil sulfonate yield.

Table Il.-Sulf0rmti0n of Necton 60-Compnrison 10 C. and 70 C. treating temperature 1 BOD-Based on distillate.

This shows that when the feed stock is treated at 10 C. and conventionally neutralized a larger yield of higher molecular weight can be obtained than when treated at 70 C. A 200% higher yield of sulfonate of equal quality may be had by extracting the total emulsion rather than the acid oil layer. On the other hand if the extraction process is not used the sulfonate obtained from the total emulsion would be of inferior quality.

EXAMPLE 3 In a typical low temperature process, 1000 ml. of a solvent refined coastal lubricating oil stock having a viscosity of 840520 SSU/ F. were diluted with 100%) ml. of liquid S0 ml. of 30% oleum are added maintaining the temperature at 10 C. This reaction mixture has a mol ratio of approximately 5 mols of 50 mol of sulfonatable hydrocarbon. Agitating for one hour, the S0 was removed by vacuum stripping still maintaining the temperature at 10 C. The total reaction mass is quenched with approximately 5200 ml. of 50% isopropyl alcohol and neutralized with 290 ml. of 50% NaOH and 600 ml. saturated Na CO solution maintaining the temperature below 10 C.

The separated layers had the following volumes:

Ml. Mineral oil 792 Alcoholic soap solution 4985 Salt layer 1850 The alcoholic soap solution contained 5.02 gm. total sulfonate/ 100 ml. having an average molecular weight of 400 and 0.48 gm. oil/ 100 ml.

Twelve hundred milliliters of crude alcoholic soap solution were countercurrently fractionated in an extractor. Of the 60.2 gms. total sulfonate charged 18.0 vol. percent based on original oil feed were oil soluble sulfonates (482 M. W.) and 5.8 vol. percent were water soluble sulfonates (M. W. 264). The neutral oil yield was 79.2%

Example 3 presents a value that is had by extractive processing. For example, by conventional treating operations a sulfonate of low molecular weight (400) may be obtained which is considered of inferior quality as a lube oil additive. However, by employing the extractive feature taught in this invention the inferior sulfonate can be refined and a sulfonate of high quality obtained.

Similar results were obtained with other feed stocks such as phenol extracts of lubricating oils and C polypropyl benzene alkylates.

The process of this invention obtains oil soluble sulfonate yields of 50 to 100% higher than those obtained by comparable processes. Improved recovery of both the water and oil soluble sulfonates are obtained because of the prevention of emulsion formation and product degradation. It should be emphasized that all of the factors involved in the combination process contribute to these improvements.

The oil soluble sulfonates produced in the present process are substantially free from water soluble or sludge type sulfonates always found in conventional mahogany sulfonate products. This makes them particularly useful in applications where traces of these impurities are highly undesirable, for example, the present sulfonates make excellent engine detergents and rust preventives.

It is to be understood that the invention is not limited to the specific examples which have been otfered merely as illustrations since modifications may be made without departing from the spirit of this invention.

What is claimed is:

1. A process of preparing and recovering superior oilsoluble sulfonates in increased yields which comprises contacting a petroleum hydrocarbon oil feed stock dissolved in liquid sulphur dioxide at a maximum temperature of 10 C. with concentrated sulfuric acid in a single treat, removing the sulfur dioxide, neutralizing the resultant total mixture in the presence of -150 volume percent based on the feed stock of a C -C alcohol with an alkali agent thus forming a product emulsion, countercurrently fractionating the total product emulsion in the presence of a hydrophobic organic solvent extractant capable of selectively extracting oil-soluble sulfonates in an extraction zone at a temperature above F., forming and recovering an extract phase containing oil-soluble sulfonates of high quality.

2. A process in accordance with claim 1 wherein 10-25 volume percent of oleum is employed as the sulfonating agent.

3. A process in accordance with claim 1 wherein a neutralization is conducted at a temperature in the range of 0 to +10 C.

References Cited in the file of this patent UNITED STATES PATENTS 1,240,523 Wolfl? Sept. 18, 1917 2,149,661 Brandt Mar. 7, 1939 2,149,662 Brandt Mar. 7, 1939 2,279,086 Bergstrom Apr. 7, 1942 

1. A PROCESS OF PREPARING AND RECOVERING SUPERIOR OILSOLUBLE SULFONATES IN INCREASED YEILDS WHICH COMPRISES CONTACTING A PETROLEUM HYDROCARBON OIL FEED STOCK DISSOLVED IN LIQUID SULPHUR DIOXIDE AT A MAXIMUM TEMPERATURE OF -10*C. WITH CONCENTRATED SULFURIC ACID IN A SINGLE TREAT, REMOVING THE SULFUR DIOXIDE, NEUTRALIZING THE RESULTANT TOTAL MIXTURE IN THE PRESENCE OF 50-150 VOLUME PRECENT BASED ON THE FEED STOCK OF A C1-C4 ALCOHOL WITH AN ALKALI AGENT THUS FORMING A PRODUCT EMULSION, COUNTERCURRENTLY FRACTIONATING THE TOTAL PRODUCT EMULSION IN THE PRESENCE OF A HYDROPHOBIC ORGANIC SOLVENT EXTRACTANT CAPABLE OF SELECTIVELY EXTRACTING OIL-SOLUBLE SULFONATES IN AN EXTRACTION ZONE AT A TEMPERATURE ABOVE 125*F., FORMING AND RECOVERING AN EXTRACT PHASE CONTAINING OIL-SOLUBLE SULFONATES OF THIGH QUANLITY. 